1. Field of the Invention
The present invention relates to a method for operating a computer system with power saving function, and more particularly to a method for operating a computer system whose maloperation or halt is capable of being prevented during system management interrupt (SMI) for power saving operation.
2. Background of Related Art
At present, most computer systems have a power saving function so as to reduce power consumption thereof. Generally, power supplies for display apparatus such as cathode ray tube (CRT) display monitor apparatuses commonly used with computer systems are designed to provide the necessary voltages and currents within the desired specifications using internal control. As for a video display apparatus, typically, the power supply system thereof is provided with a power-off circuit for interrupting the electrical power supply to the display apparatus during a power off state.
In a video display apparatus having audio circuitry, video power savings for video circuitry are achieved by display power management signaling (DPMS) control recommended by video electronics standard association (VESA). It is well known that the DPMS power supply modes may be classified into a normal mode, a standby mode, a suspend mode and a power-off mode. During a normal operation mode (or full on mode) of the power management, all subsystems, such as an HDD (hard disk drive), a monitor and the like, are fully powered an the microprocessor chip is then operating at full speed. The computer systems remain in this state as long as it detects activity or if the power management controller has been at a disable state. If the computer system is not used for a predetermined amount of time, the power management controller is changed to a stand-by-mode. In this state the microprocessor clip is set to the lowest speed of low frequency possible and the power management controller is put into a reduced power state. The system continually monitors the wake-up activities from subsystems, such as a keyboard, a mouse, a communication port or an application program during this mode. This, in this state the power consumption can be largely reduced. During a suspend mode, all of the devices including the memory contents are saved to a separate disk portion and the entire computer is turned off. In this state, the contents are saved indefinitely until the computer system is resumed by hitting the power on button. Other than off, this mode is the lowest power state and is fixed to suspend to disk. For example, even a DC voltage is not applied to the microprocessor chip, and a DC voltage is not supplied to the most of the subsystems with the exception of subsystems necessary for restoring them to a normal operation mode. Finally, in case of a power off mode, the computer system is powered off so that the operation thereof is halted. See, for example, U.S. Pat. No. 5,548,763 for Desk Top Computer System Having Multi-Level Power Management issued to James L. Combs et al.
Herein, a "power saving function" means that most components of a computer system are halted to minimize power consumption, when the computer system is not used for a preset time, or when the computer system is operated with a battery mounted therein and the battery voltage is less than a preset voltage level. A "SAVE.sub.-- TO.sub.-- DISK" function is one of several ways that are used to perform a power saving function, e.g., a suspend operation in computer systems. The "SAVE.sub.-- TO.sub.-- DISK" function means that, when a computer system is not used more than a preset time, or when a specific key is pressed by a user, presently processing data and status information of the computer system are automatically saved in an auxiliary storage device, i.e., a hard disk and then the computer system is completely or partially powered off.
Generally, a computer system is broadly provided with a power supply, a microcomputer for functioning as a power supply controller, a CPU (central processing unit), a bus, a BIOS (basic input/output system) storage memory, a main memory consisting of RAM (random access memory), and an auxiliary memory consisting of a hard disk, etc.
The power supply distributes power from an AC adapter or a battery to respective components of the computer system. The microcomputer is provided to control the power supply in response to a power-on signal from a power-on switch and enable power from the power supply to be supplied to the respective components of the computer system. The microcomputer is also provided to control the power supply so as to enable the supply of power to the respective components to be shut down after the completion of the SAVE.sub.-- TO.sub.-- DISK operation. Namely, the microcomputer generates an SMI (system management interrupt) request signal which is to manage the computer system. The SMI request signal includes interrupt signals which are generated to perform power management of the computer system.
Next, the CPU detects the SMI request signal and performs an SMI process routine which is stored in the BIOS storage memory. If the SMI request signal is detected as a control signal used to perform the SAVE.sub.-- TO.sub.-- DISK operation, all the status information that has been set in the computer system are saved in the auxiliary memory. After this operation, the microcomputer controls the power supply so as to enable minimal power necessary for minimal operation of the computer system to be supplied.
On the other hand, if a power-on switch is at an ON state after the completion of the SAVE.sub.-- TO.sub.-- DISK operation, a resume operation is performed so the computer system can be recovered to a normal state in the below-mentioned manner.
The microcomputer controls the power supply to enable the supply of power to be supplied again from the power supply to the computer system. A POST (power-on-self-test) routine stored in the BIOS storage memory is then performed. At this time, it is determined whether or not the resume operation is needed. If the resume operation is needed, the resume operation is then performed. When the resume operation is completely finished, the computer system is recovered to an operational state prior to the SAVE.sub.-- TO.sub.-- DISK operation.
Conventional systems for computers having a data recovering function in the event of a power failure are illustrated, for example, see U.S. Pat. No. 5,708,820 for Network Hibernation System For Suspending And Resuming Operation Of Computer System Operable In Network Environment In Event Of Power Failure Or Period Of inactivity issued to Noh-Byong Park et al., U.S. Pat. No. 5,485,623 for Information Processor having High Speed And Safety Resume system issued to Yoshiki Kurokawa et al., U.S. Pat. No. 5,414,861 for Data Protection System Using Different Levels Of Reserve Power To Maintain Data In Volatile Memories For Any Period Of Time issued to Randall Horning, U.S. Pat. No. 5,396,637 for Data Processing System With Power-Fail Protected Memory Module issued to John C. Harwell et al., U.S. Pat. No. 5,204,963 for Method And Apparatus For A Backup Power Controller for Volatile Random Access Memory issued to Eric S. Noya et al., U.S. Pat. No. 5,018,148 for Method And Apparatus For Power Failure Protection issued to Rameah U. Patel et al., U.S. Pat. No. 4,763,333 for Work-Saving System For Preventing Loss In A Computer Due To Power Interruption issued to Kerry Byrd, and U.S. Pat. No. 3,801,963 for Method and Apparatus For Transferring Data From A Volatile Data Store Upon The Occurrence Of A Power Failure In A Computer issued to Kun-Chao C. Chen. These systems usually include a memory transfer device for transferring data stored in a volatile memory into a non-volatile memory (i.e., a memory that is capable of retaining data without power) upon a power termination or a power failure so that, when power is restored, a data refreshing device could transfer the data from the non-volatile memory back into the volatile memory and thereby restoring the computer to its exact state before the power failure, right down to the cursor position on the screen.
Separately, conventional systems for computers having a power saving function are illustrated, for example, in U.S. Pat. No. 5,021,983 for Suspend/Resume Apparatus And Method For Reducing Power Consumption In Battery Powered Computers issued to Au H. Nguyen et al. This system, for example, allows the user to turn off the computer during any period of non-use and to subsequently resume operation of the computer to exactly the same place before the shutdown.
Recently, computer operating systems utilizing an APM (advanced power management) function is on an increasing trend. See, for example, U.S. Pat. No. 5,638,541 for System And Method For Managing Power On Desktop System issued to Shivaprasad Sadashivaiah and U.S. Pat. No. 5,560,023 for Automatic Backup System For Advance Power Management issued to Dwayne T. Crump et al. The APM function is defined as a kind of power saving function that even operation systems (OS) can reduce power consumption in accordance with operational states of the computer system. In a computer system having an OS with APM function loaded therein, when a resume operation is performed after the SAVE.sub.-- TO.sub.13 DISK operation, a resume operation stored in the BIOS storage memory is performed and then a resume function implemented in the loaded OS is performed. It is known in this art that it takes the computer system about 30 seconds to perform the resume operation related to the OS.
However, when a SMI request signal for SAVE.sub.-- TO.sub.-- DISK operation is generated during the OS-related resume operation, the computer system is halted or not normally operated because the OS-related resume operation is not completely finished.